Treadmills enable a person to walk, jog, or run for a relatively long distance in a limited space. Treadmills can be used for physical fitness, athlete training and therapeutic uses for the treatment of medical conditions. It should be noted that throughout this document, the term “run” and variations thereof (e.g., running, etc.) in any context is intended to include all substantially linear locomotion by a person. Examples of this linear locomotion include, but are not limited to, jogging, walking, skipping, scampering, sprinting, dashing, hopping, galloping, side stepping, shuffling etc. The bulk of the discussion herein is focused on training and physical fitness, but persons skilled in the art will understand that all of the structures and methods described herein are equally applicable in a medical therapeutic applications.
A person running generates force to propel themselves in a desired direction. To simplify this discussion, the desired direction will be designated as the forward direction. As the person's feet contact the ground (or other surface), their muscles contract and extend to apply a force to the ground that is directed generally rearward (i.e., has a vector direction substantially opposite the direction they desire to move). Keeping with Newton's third law of motion, the ground resists this rearwardly directed force from the person, resulting in the person moving forward relative to the ground at a speed related to the force they are creating. While the prior discussion relates solely to movement in the forward direction, persons skilled in the art will understand that this can mean movement in any direction, for example side to side, backward/reverse, any desired direction.
To counteract the force created by the treadmill user so that the user stays in a relatively static fore and aft position on the treadmill, a running belt of a treadmill is driven or rotated (e.g., by a motor). Thus, in operation, the running belt moves at substantially the same speed as the user, but in the opposite direction. In this way, the user remains in substantially the same relative position along the treadmill while running.